418 THE DESCENT OF MAN 



ble; but if it should hereafter be found that the formation 

 of an ocellus is due to some change in the tissues of the 

 wings, for instance, occurring at a very early period of 

 development, we might expect, from what we know of the 

 laws of inheritance, that it would be transmitted to both 

 sexes, though arising and perfected in one sex alone. 



On the whole, although many serious objections may be 

 urged, it seems probable that most of the brilliantly colored 

 species of Lepidoptera owe their colors to sexual selection, 

 excepting in certain oases, presently to be mentioned, in 

 which conspicuous colors have been gained through mimicry 

 as a protection. From the ardor of the male throughout 

 the animal kingdom, he is generally willing to accept any 

 female; and it is the female which usually exerts a choice. 

 Hence, if sexual selection has been ef3ficient with the 

 Lepidoptera, the male, when the sexes differ, ought to be 

 the more brilliantly colored, and this undoubtedly is the 

 case. When both sexes are brilliantly colored and resemble 

 each other, the characters acquired by the males appear to 

 have been transmitted to both. We are led to this conclu- 

 sion by cases, even within the same genus, of gradation 

 from an extraordinary amount of difference to identity 

 in color between the two sexes. 



But it may be asked whether the differences in color 

 between the sexes may not be accounted for by other means 

 besides sexual selection. Thus the males and females of 

 the same species of butterfly are in several cases known" 

 to inhabit different stations, the former commonly basking 

 in the sunshine, the latter haunting gloomy forests. It is 

 therefore possible that different conditions of life may have 

 acted directly on the two sexes; but this is not probable," 

 as in the adult state they are exposed to different conditions 

 during a very short period; and the larvae of both are ex- 



" H. W. Bates, "The Naturalist in the Amazons," vol. ii., 1863, p. 228. 

 A. R. Wallace, in "Transact. Linn. Soc," vol. xxv., 1865, p. 10. 



'" On this whole subject see "The Variation of Animals and Plants under 

 Domestication," 1868, vol. ii. chap, xxiii. 



